Vortex-assisted natural deep eutectic solvent microextraction using response surface methodology optimization for determination of orthophosphate in water samples by molybdenum blue method.

A new, rapid, and efficient microextraction technique named vortex-assisted natural deep eutectic solvent microextraction has been developed for the preconcentration and determination of orthophosphate in real water samples. The method is based on the formation of the phosphomolybdenium blue complex followed by proposed microextraction procedure and subsequent spectrophotometric determination in a microcell. Screening study for the optimal composition of natural deep eutectic solvent was initially performed with different solvents, including choline chloride as hydrogen bond acceptor and different hydrogen bond donors. A ternary mixture of glucose-choline chloride-water was used as the most efficient extraction solvent. Response surface methodology based on the central composite design was used to optimize experimental parameters. Under optimal conditions, the calibration graph for orthophosphate determination was linear over the range of 2.0-80.0 µg/L (correlation coefficient of 0.9971) with a detection limit of 0.2 µg/L. The repeatability, reproducibility, and relative error values of the method were below 7%, indicating acceptable precision and accuracy. This approach, using natural deep eutectic solvent as an eco-friendly solvent with high solubilization power and vortex mixing as an alternative energy source, represents a promising choice for a green separation and preconcentration methodology for determination of orthophosphate in real water samples.